1. Field of the Invention
The present invention relates to an image processing apparatus and an image processing method using a scanner, and a program to execute the image processing method.
2. Description of the Related Art
There exists a technique of “super resolution processing” and “super resolution conversion” to increase resolution by using a plurality of pieces of image data of certain resolution. The technique enables conversion of a low-resolution image to a high-resolution image, so that a high-resolution image can be obtained in a conventional device (“Super Resolution Processing by Plural Number of Lower Resolution Images” Ricoh Technical Report No. 24, November, 1998).
The super resolution technique is widely applied in a field of moving image processing and the like because execution of the super resolution technique requires a plurality of frames of image data in which reading positions on an original image are slightly different in units of sub-pixels (a unit smaller than a pixel).
In the super resolution processing, however, a plurality of frames of image data are necessary to generate image data of one pixel of a high-resolution image, which causes a problem of a large amount of data and calculation.
Conventionally, the amount of calculation has been reduced by determining the number of pieces of image data on which super resolution processing is performed, in accordance with the size of a target image area (Japanese Patent Laid-Open No. 2006-092450).
However, line sensors are typically used as a reading device in an image processing apparatus, such as an MFP (Multifunction peripheral) or a scanner. That is, one reading operation can read data of one page.
The above-described reading device reads an original image by using a group of pixel sensors that are horizontally placed in a main scanning direction at intervals of an integral multiple of a pixel. Thus, the reading device is disadvantageously incapable of reading the original image by slightly shifting the reading position of pixels in units of sub-pixels in the main scanning direction.
Under the above-described circumstances, it is difficult to perform super resolution processing in an MFP. The performance of a device needs to be enhanced in order to obtain high-resolution images, which results in high cost.
In recent years, an MFP including a color scanner and a monochrome printer has become widespread, enabling transmission of color information. However, the printer unit therein can accept only monochrome data and thus the color information obtained through the color scanner is lost in a copy operation, so that an advantage of the color information is not fully utilized.